AMERICAN DIPTERA. 263 



6. Abdomen yellowish at base basalis Loew. 



Abdomen uuicolorous, dark 7. 



7. Stigma obsolete 8. 



Stigma at least fuscous 12. 



8. Legs fuscous to black 9. 



Legs paler 11. 



9. Thorax 4-vittate qnadrivittata Meigen. 



Thorax evittate 10. 



10. Thoracic hairs blackish ; halteres whitish ; veins pale, -leucoptera Loew. 

 Thoracic hairs pale ; halteres infuscated ; veins dark bella sp. uov. 



11. Abdomen opaque niacroptera Loew. 



Abdomen shining congregaria sp. nov. 



12. Front metatarsi not thickened ; antennse at least three times as long as the 



head, its style twisted joltusoui t'oquillett. 



Male front metatarsi somewhat thickened; antennae shorter, the style 

 straight 13. 



13. Palpi black 14. 



Palpi testaceous 23. 



14. Knees more or less yellowish 15. 



Knees black 18, 



15. Wings blackish tristis Loew. 



Wings cinereous 16. 



16. Knob of halteres black miitabilis Loew. 



Knob of halteres fuscons 17. 



17. Thorax vittate triTittata Loew. 



Thorax evittate iiiigax sp. nov. 



18. Thorax vittate IS. 



Thorax evittate 20. 



19. Pile of abdomen yellow cana Coquillett. 



Pile of abdomen black bacnlifer sp. nov. 



20. Abdomen opaque unicolor Loew. 



Abdomen somewhat shining 21. 



21. Wings dusky velutina Loew. 



Wings suhcinereous 22. 



22. Thorax shining atra Loew. 



Thorax velutinous carboiiaria sp. nov. 



23. Abdomen at base fuscous ... -baNalis Loew. 



Abdomen wholly black 24. 



24. Femora, except tip, black ; thorax with two obsolete vittse. 



breTipila Loew. 

 Femora more or less yellow ; thorax evittate 25. 



25. Knob of halteres black '. 26. 



Knob of halteres yellowish 27. 



26. All the femora testaceous gracilis Loew. 



The hind femora not testaceous nigriventris Loew. 



27. Pile of middle tibise long ... »$eriata Loew. 



No long hairs on middle legs; second joint of front tarsi of the male not pro- 

 ceeding from the tip of the metatarsus Wheeleri Melander. 



